This invention relates to a V type engine and more particularly to an improved camshaft drive arrangement for a V type engine.
There are many advantages to the use of engines having their cylinders arranged in banks that are disposed at angular relationship to each other to provide a V shaped configuration for the engine. Normally, such constructions permit an overall shortening of the length of the engine for a given number of cylinders and to provide an otherwise more compact assembly. However, the compact assemblage of such V type engines give rise to certain problems in connection with their construction and design. Specifically, because of the compact arrangement the drive of the camshafts for such an engine can present some problems, particularly if one or more overhead camshafts are employed for the engine.
As is well known, it is necessary for four cycle engines to drive the camshafts at one half the speed of the engine output shaft so as to afford the proper timing relationship. However, when such a two to one ratio is achieved in a single pass, then the size of the individual sprockets on the camshafts can become quite large and can make placement a problem. In order to overcome these difficulties, it has been proposed to provide the reduction ratio in two passes between the crankshaft and the camshaft. In addition to this reason, there are other reasons why it may be desirable to drive the camshafts rather than directly from the engine crankshaft from an intermediate shaft that is disposed between the camshafts and the crankshaft. Of course, if such intermediate shaft drives are employed, this can further complicate the drive mechanism in the area of the engine where the camshafts are driven.
It is also desirable to employ flexible transmitters such as chains for driving the camshafts and the intermediate shafts. However, with flexible transmitters, if not essential, it is at least desirable to insure a tensioning mechanism for the transmitter and also some form of guide that will insure that the transmitter cannot become displaced from the driving and driven sprockets. Of course, when such an arrangement is employed with a V type engine, this can present considerable problems due to the compact construction in the area where the transmitters lie.
It is, therefore, a principal object of this invention to provide an improved arrangement for driving the flexible transmitters of a V type engine for a camshaft drive and for tensioning and guiding these transmitters.
It is a further object of this invention to provide an improved, compact tensioner and guide arrangement that can be positioned in the area between the cylinder banks for operating with the flexible transmitters in this area.